Cortisol, 24-Hour Urine — 2 Days Post-High-Dose Dexamethasone, Mass Concentration
Measures urinary cortisol after a prescribed high-dose dexamethasone challenge to help evaluate possible Cushing syndrome.
["This suppression test can help determine whether excess cortisol production is present."]
Key facts at a glance
- LOINC
- 57631-4
- Short code
- A-cortolone 2D p high Dex 24h Ur-mCnc
- Synonyms
- A-cortolone 2D p high Dex 24h Ur-mCnc
- Category
- liver
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- Ref low
- 20
- Ref high
- 400
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 82670
- Specimen volume
- 10 mL
- Stability
- Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
What is this test?
This test measures the amount of cortisol released in your urine over 24 hours after you have taken a prescribed high dose of dexamethasone. Cortisol is a hormone that helps the body manage stress and regulate several important functions.
Why might I need this test?
It may be used to help investigate Cushing syndrome or other causes of excess cortisol. Dexamethasone normally suppresses cortisol production, so the pattern of cortisol levels during this test provides information about the body's response.
How is the test performed?
You collect all urine produced during a specified 24-hour period, usually starting in the morning. The laboratory measures the cortisol concentration in the collected urine, and the result is interpreted along with the dexamethasone schedule and other clinical findings.
How do I prepare for the test?
Take dexamethasone exactly as prescribed and complete the urine collection for the full 24 hours. Your clinician or laboratory will provide the collection container, start time, and any special instructions; do not change or stop the medication without medical guidance.
Reference range
Premenopausal: 20-400 pg/mL; Postmenopausal: <30 pg/mLN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
If cortisol is suppressed as expected after high-dose dexamethasone, this generally argues against Cushing syndrome. Failure to suppress may prompt additional testing for a cortisol-producing condition. Results must be interpreted by a clinician because the response can be affected by medications, kidney function, and the timing of urine collection and dexamethasone dosing.
Short name
24-hour urine cortisol after high-dose dexamethasone
Frequently asked questions
Is this the same as a routine urine cortisol test?
What happens if I miss part of the urine collection or a dose?
Will an abnormal result diagnose Cushing syndrome?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy